Electric to shed

[tombarton]

Shed is 15 feet from house 200 amp panel. Want to add a box to shed to feed one light and one small 5K air conditioner. A 20 amp breaker already feeds one outdoor GFI plug nearby, attached to house. Got new 12/2 in conduit and want to pig tail it off that existing 20 amp GFI plug To source the shed. Can I do this safely as planned?

 

[mike93lx]

What kind of wire is it? Hopefully not nm-b (romex) as it isn't allowed outdoors

Yes, with the right wire, you can extend the existing 20a circuit to your shed

 

[tombarton]

Thx. So what's the no no safety issue running rwo separate 12/2 underground rated wires to a shed. What's the reasoning behind it? If they are 6 ft apart and forever separate wires into a shed, why does code say it's a big no no?

 

[mike93lx]

with separate feeds, you need to take multiple steps to disconnect power to a structure. Also, it could create parallel pathways.

I believe that the latest code revision has changed this, but I'm not certain.

if you are considering running two circuits, just do a multi wire branch circuit. 12/3 uf-b or thwn-2 in conduit, fed by a two pole 20a breaker

 

[theoldwizard1]

if you are considering running two circuits, just do a multi wire branch circuit. 12/3 uf-b or thwn-2 in conduit, fed by a two pole 20a breaker

Don't quote me, but if it is a separate building, I think code requires a disconnect in the building.

 

[AffableCurmudgeon]

You are only 15 feet away. Your needs may change. If I were you, I would run a new larger wire and be set for future growth.

 

[wyliesdiesels]

Thx. So what's the no no safety issue running rwo separate 12/2 underground rated wires to a shed. What's the reasoning behind it? If they are 6 ft apart and forever separate wires into a shed, why does code say it's a big no no?

can you post a picture of the wire you have

NM-b is not rated for outdoor or underground use regardless of conduit.

 

[alfredeneuman]

I believe that the latest code revision has changed this, but I'm not certain.

If your jurisdiction recognizes the 2020 or 2023 NEC, the single feed to a detached building is no longer an issue. You can have up to 6 feeds, but each needs a labeled, separate disconnecting means grouped together, in separate enclosures

 

[sparky 1971]

If your jurisdiction recognizes the 2020 or 2023 NEC, the single feed to a detached building is no longer an issue. You can have up to 6 feeds, but each needs a labeled, separate disconnecting means grouped together, in separate enclosures

The grouping is fine and makes perfect sense but I have issues with the separate enclosures. Ain't no way this fat guy is going to run six 20 amp circuits to a separate structure, but if I were to do so, I would think a six gang box would be better. The same goes for a 400 amp service and needing each of the 200 amp breakers behind it's own door (when installed outside as the emergency disconnect). Wouldn't it be easier for the fireman to open one door and kill both breakers even if one of them doesn't need to be shut off because it's for a shop? They could be labeled on the inside just as well if not better than the outside just to try to eliminate confusion.

 

[tombarton]

I already have 12/2 buried in conduit to the shed so to late to change wire. My first mistake. If I add a cut off breaker on the shed and keep the air conditioner to small at 5 k btu plus one shed light, I should be ok. Yes? Reaction appreciated. Just curious as to whats the reading behind code? Parallel pathways.? What the hell is that about? . Where’s the danger there. Two runs 6 ft apart buried parallel 15 ft long to a small shed. What’s the danger look like? I can live with it just a homeowner ya know what’s the reasoning here. In my house I have parallel lines all over the place. Difference must be related to it being outdoors in the ground to a shed 15 ft away from the house. I guess. What goes wrong worse case scenario

What kind of wire is it? Hopefully not nm-b (romex) as it isn't allowed outdoors

Yes, with the right wire, you can extend the existing 20a circuit to your shed

wire is rated underground 12 2 ya know the hard stuff that takes a day to strip

 

[tombarton]

The grouping is fine and makes perfect sense but I have issues with the separate enclosures. Ain't no way this fat guy is going to run six 20 amp circuits to a separate structure, but if I were to do so, I would think a six gang box would be better. The same goes for a 400 amp service and needing each of the 200 amp breakers behind it's own door (when installed outside as the emergency disconnect). Wouldn't it be easier for the fireman to open one door and kill both breakers even if one of them doesn't need to be shut off because it's for a shop? They could be labeled on the inside just as well if not better than the outside just to try to eliminate confusion.

So 2 shut off boxes in two locations for the firemen. I can do that. And little danger with two 12/2 buried lines to a shed? do they have to be buried separately I wonder?

 

[sparky 1971]

So 2 shut off boxes in two locations for the firemen. I can do that. And little danger with two 12/2 buried lines to a shed? do they have to be buried separately I wonder?

AFAIK they can be in same trench, but I've never had to find out. If you're going back to the panel to get circuit #2 why not just bring a 12/3 and have two circuits exclusively for the shed? Then there's nothing to worry about and you can use one two pole switch for a disconnect

 

[dscheidt]

The grouping is fine and makes perfect sense but I have issues with the separate enclosures. Ain't no way this fat guy is going to run six 20 amp circuits to a separate structure, but if I were to do so, I would think a six gang box would be better. The same goes for a 400 amp service and needing each of the 200 amp breakers behind it's own door (when installed outside as the emergency disconnect). Wouldn't it be easier for the fireman to open one door and kill both breakers even if one of them doesn't need to be shut off because it's for a shop? They could be labeled on the inside just as well if not better than the outside just to try to eliminate confusion.

Reduces the maximum available fault current, which reduces the maximum energy an arc flash can have.

 

[sparky 1971]

Reduces the maximum available fault current, which reduces the maximum energy an arc flash can have.

The 400 amp meter setting with two 200 amp breakers is the same as the pre 2020 service with the difference being that instead of both breakers being behind a 12" wide door, they are now behind separate 6" wide doors. Fault current isn't changed by adding another step to shut everything off and it's only a consideration in commercial services.

 

[tombarton]

Thx. So what's the no no safety issue running rwo separate 12/2 underground rated wires to a shed. What's the reasoning behind it? If they are 6 ft apart and forever separate wires into a shed, why does code say it's a big no no?

Apparently the reasoning 2 separate circuits are not allowed is an unknowing resident might think they have turned off the power to the shed by flipping the panel breaker when in fact one plug in the shed is still hot! Dangerous! Got my answer thx. I'll follow code.

 

[sparky 1971]

Apparently the reasoning 2 separate circuits are not allowed is an unknowing resident might think they have turned off the power to the shed by flipping the panel breaker when in fact one plug in the shed is still hot! Dangerous! Got my answer thx. I'll follow code.

That probably was the reason, but as of the adoption of the 2020 NEC, more than one circuit can be run to another building. The safety factor is why disconnects are supposed to be grouped together.

 

[thool]

To avoid creating another thread with similar content, I'm going to piggyback on this one.

If someone has a shed that is about 3 feet from a 100A mobile home, and they want to provide 15A power to a single outlet and a couple switched hardwired LED lights in the shed, how would this imaginary person go about this safely? Would a GFCI breaker, followed by direct burial UF-B be appropriate?

Thinking 2 boxes: the first in line would be a 2-gang with a switched outlet, the second/downstream would be a single for the light switch.

The most the outlet will be for would be charging batteries for lawnmower, cordless tools, sometimes a boat battery, wired drill. Possibly a small 2 gallon air compressor.

 

[sparky 1971]

To avoid creating another thread with similar content, I'm going to piggyback on this one.

If someone has a shed that is about 3 feet from a 100A mobile home, and they want to provide 15A power to a single outlet and a couple switched hardwired LED lights in the shed, how would this imaginary person go about this safely? Would a GFCI breaker, followed by direct burial UF-B be appropriate?

A GFCI breaker is fine, but I would use a regular breaker and GFCI receptacles

Thinking 2 boxes: the first in line would be a 2-gang with a switched outlet, the second/downstream would be a single for the light switch.

The most the outlet will be for would be charging batteries for lawnmower, cordless tools, sometimes a boat battery, wired drill. Possibly a small 2 gallon air compressor.

You need a disconnect on or in the shed that will shut everything off. The first box, whether on the outside or inside should have a switch that kills everything in there and from there you can split lights and receptacles.

 

[thool]

A GFCI breaker is fine, but I would use a regular breaker and GFCI receptacles

If I used a plain breaker, then wouldn't everything between it and the GFCI receptacle be unsafe?

You need a disconnect on or in the shed that will shut everything off. The first box, whether on the outside or inside should have a switch that kills everything in there and from there you can split lights and receptacles.

Is there a special part for the disconnect, or would an ordinary switch be sufficient?

 

[sparky 1971]

If I used a plain breaker, then wouldn't everything between it and the GFCI receptacle be unsafe?

What is there to be unsafe? It's either going to be three wires in conduit or three wires in a cable assembly (UF) with no devices, the only real concern would be if the conductors were cut and the grounding conductor should take care of that. If you want to use a GFCI breaker, then by all means, go for it. The lights in the shed don't have to have GFCI protection unless they plug in and a GFCI breaker is a good way to be standing in the dark some evening.

Is there a special part for the disconnect, or would an ordinary switch be sufficient?

A plain old single pole switch will work just fine.

 

[wyliesdiesels]

If I used a plain breaker, then wouldn't everything between it and the GFCI receptacle be unsafe?

unless the wires underground get cut, there shouldnt be an issue.

the problem with using a GFCI breaker in this scenario is if it trips and youre in the shed, youll be left in the dark. better to have a receptacle GFCI to keep the lights on

 

[75gmck25]

You also have the option to use 12/3 or 14/3 UF-B and at the shed you can break it out into two circuits and use a GFCI on each circuit. However, it sounds like two circuits are more than you need for your requirements.

 

[thool]

You also have the option to use 12/3 or 14/3 UF-B and at the shed you can break it out into two circuits and use a GFCI on each circuit. However, it sounds like two circuits are more than you need for your requirements.

Thanks, but all I need is the 1 circuit.

 

[ipgenie]

Another option I've seen that I 'think' is kosher is to put a GFCI receptical on the house at the panel, then use an extension cord to connect the shed wiring to that receptical. Basically what an RV uses. The cord could be hard wired on the shed side or connected to a generator inlet. Unplugging the cord from the house provides the means of disconnect and the full path is GFCI protected.

If course this means you would be OK with a 3 foot cord between buildings which probably doesn't work if it crosses a sidewalk.

 

[mike93lx]

Another option I've seen that I 'think' is kosher is to put a GFCI receptical on the house at the panel, then use an extension cord to connect the shed wiring to that receptical. Basically what an RV uses. The cord could be hard wired on the shed side or connected to a generator inlet. Unplugging the cord from the house provides the means of disconnect and the full path is GFCI protected.

If course this means you would be OK with a 3 foot cord between buildings which probably doesn't work if it crosses a sidewalk.

Cords are for temporary use only. It will function but really isn't the right way to do it